RUBUS STRIGOSUS. 97 



R. deliciosus, as would be expected. Of Apis, 56 individuals went to the 

 raspberry and 16 to the salmonberry, the preponderance of the former 

 being reversed in the second experiment. The number of visitors belonging 

 to Bombus was nearly the same for both experiments, viz, 17 and 19, and 

 they were also more abundant on R. strigosus in the first case and on R. 

 deliciosus in the second. The ratio of attraction to bees was almost exactly 

 the reverse in the two instances. It is also interesting to note that they made 

 an average of 7 visits to the raspberry to 4 for the salmonberry. 



Summary. — Rubus strigosus is evidently much more attractive than 

 R. deliciosus, as shown bj' the fact that the total number of visitors in the 

 five periods was four times greater. However, this was true only for the 

 bees, though they furnished nearly the entire number, since the flies and 

 butterflies went only to the more visible and accessible flowers of the salmon- 

 berry. The raspberry held its advantage, whether used as the standard 

 plant or the bouquet, except in the last experiment, where twice as many 

 bees went to R. deliciosus. The constancy of the honey-bee was high in 

 the first four cases, viz, 221 visitors for R. strigosus to 9 for R. deliciosus, 

 but it was in abeyance in the last, in which twice as many went to the latter 

 as to the former. As a whole, Bombus was inconstant, 24 going to the one 

 and 23 to the other, while the numbers for the other bees were too small 

 to be significant, twice as many preferring R. strigosus, however. 



RUBUS STRIGOSUS AND OPULASTER. 

 Comparison. — The flowers of Opulaster are about half as large as those 

 of the raspberry, but this is more than offset by their grouping in corymbs 

 and the position of the latter at or near the ends of the branches. The 

 spreading petals make the corymb verjr conspicuous, and at a distance it 

 assumes a uniformly white appearance. The nectar is less abundant in 

 Opulaster, but this is somewhat compensated by the large number of flowers 

 in a cluster and by the open nature of the cup. The stamens are also 

 less numerous and the amount of pollen available is considerably less. 



Summary. — The total number of visitors was 138 for Rubus and 137 

 for Opulaster, indicating that they are equally attractive. However, the 

 former was more than twice as attractive to bees, the ratio being 137:64, 

 and overwhelmingly so to honey-bees, 85 of which visited the raspberry and 

 only 1 the nine-bark. Andrena crataegi was the only bee that exhibited 

 a marked preference for Opulaster, the ratio being 46:7. The behavior of 

 the flies was exactly opposite to that of the bees, 73 going to the nine-bark 

 and one to the raspberry. This appears to be readily explained by the 

 fact that the flowers of the former were more easily seen and the nectar 

 more accessible. The smaller amount of nectar and the ease with which 

 it can be obtained make clear the reason why the bees and Apis in particular 

 preferred the raspberry with its less conspicuous flowers and larger store 

 of nectar less accessible to flies. 



COMPETITION OF RUBUS WITH FRASERA, CLEOME, ETC. 



Comparison. — The flowers of Jamesia americana resemble those of the 

 raspberry, but differ in forming conspicuous white clusters at the ends of 

 branches, and in having much less pollen and much more perfume. Those 



